Floor systems, particularly hardwood floor systems, are commonly supported by sleepers. Sleepers are elongated nailing strips, often of wood, laid end to end in spaced, parallel rows. A layer of hardwood floor boards or another type of wear layer is then secured to the sleepers for additional dimensional stability. If desired, one or more intermediate layers may be used between the wear layer and the sleepers. The sleepers support the other floor components in spaced relation above a base.
One recognized advantage of supporting a floor system with sleepers relates to moisture susceptibility. The components of most floor systems are made of wood. Humidity changes from season to season cause wooden components of floor systems to expand with moisture ontake and contract with moisture expulsion. Because sleepers support other components in spaced relation above the base, the sleepers limit moisture transfer between the base and these other components. Moreover, the free space between the supported components and the base enables air to circulate therebetween to minimize moisture transfer.
Because moisture-caused expansion and contraction of wooden floor system components, including the sleepers, may result in buckling or vertical raising, it is desirable to securely anchor the floor system to the base below. To prevent this vertical raising, the sleepers must be anchored. Anchoring of the sleepers provides an acceptable level of dimensional stability for the floor system, compared to free floating-type floor systems in which the sleepers are not anchored.
It is also desirable for hardwood floor systems to provide a degree of resilience. In the context of this application, resilience generally means the ability of a floor system to absorb shock upon impact and to deflect downwardly upon impact. Although other factors must be considered in determining the overall resiliency of a floor system, the capability for absorbing shock and deflecting downward are the most critical. Particularly for hardwood floors used in athletic contests, the resilience of the floor plays a major role in reducing the incidence of athletic injury. In short, if a floor provides some degree of give, the stress placed upon the musculoskeletal structure of the athlete is reduced.
It is common practice to provide resiliency for a floor system by locating compressible pads below the sleepers. The compressibility of the pad enables the sleepers and the floorboards thereabove to deflect downwardly. The amount of downward deflection and the shock absorption of the floor system will depend upon a number of factors, including the shape and composition of the pads.
Recent studies indicate that, while resiliency is important to the reduction of susceptibility to athletic injury, uniformity in resiliency is also critical. Thus, it is desirable to provide a floor system with a degree of resiliency which is uniform throughout its surface area.
Unfortunately, it has proved difficult to achieve dimensional stability, optimum resiliency and uniformity in resiliency for hardwood floors supported by sleepers. The enhancing of one of these features commonly adversely affects the others. For instance, when sleepers are supported above the base by a plurality of compressible pads and the sleepers are fastened to the base, direct fastening of the sleeper produces some initial compression, or precompression of the pads. The pads remain compressed throughout the life of the floor, even when the floor is unloaded. Because of this already compressed state, the capability of the pads for further deflection is inhibited, and the overall resiliency of the floor system is greatly reduced. On the other hand, if the floor system is free-floating, i.e. the sleepers are not anchored securely to the base, the entire floor system may be dimensionally unstable.
While some commercially available floor systems have achieved a degree of success in addressing one or more of these concerns, such floor systems tend to have a relatively high cost, due to an increase in the number or complexity of structural components required for achieving these features and the increased costs associated with shipping and installing these components. As a result, the benefits of these floor systems have been limited unnecessarily to a relatively low number of users.
It is an objective of this invention to achieve optimum dimensional stability and optimum resiliency and uniformity of resiliency for a sleeper type hardwood floor system.
It is another objective of this invention to substantially improve resiliency and dimensional stability for a relatively low cost, sleeper type hardwood floor system.
It is still another objective of this invention to enhance the dimensional stability of a sleeper-type hardwood floor system without producing a corresponding loss in resiliency, or uniformity in resiliency.
The objectives of this invention are achieved by a sleeper construction which utilizes an attachment or nailing strip supported by compressible pads above a base and a fastening arrangement which secures the sleepers directly to the base without interacting with the pads. This fastening arrangement enables the attachment strips to deflect downwardly upon impact to upper floor layers but restricts upward raising of the nailing strips beyond the initial static position of the pads. More importantly, this fastening arrangement enables the attachment strips to be anchored to the base in a manner which does not precompress the pads when the floor system is unloaded. Thus, this anchored/resilient sleeper provides optimum dimensional stability and resiliency.
Because the manner of anchoring the attachment strips does not precompress the pads or hold them in a precompressed state, an even distribution of the compressible pads along the attachment strips will assure a uniformly resilient, yet firmly anchored, floor system.
Additionally, because of its simplicity and relatively few number of parts, the embodiments of this invention provide anchoring, resiliency and uniformity in resiliency for a sleeper-type floor system at a low cost. Fabrication and installation of the sleepers is also simplified. Finally, because the fastening arrangement provides secured anchoring, the lengths of the sleepers may be increased. As a result, less waste is produced and shipping, handling and installation costs are reduced.
According to one preferred embodiment of the invention, a fastener/sleeve construction is utilized. With this embodiment, each attachment or nailing strip has at least one vertical bore extending from an upper surface to a lower surface thereof. At least two compressible pads are secured to the lower surface. The vertical bore includes an enlarged-diameter upper portion and a reduced-diameter lower portion. The sleeve resides within the lower, reduced-diameter portion, with the bottom edge of the sleeve contacting the base and the top edge of the sleeve residing adjacent the upper portion of the bore. A washer resides on top of the sleeve. Alternately, the sleeve may include an upper flange. A fastener extends downwardly through the washer, or flange, through the sleeve and into the base. An enlarged head at the top of the fastening pin engages and holds the washer, or the flange, against the bottom surface of the upper portion.
This securely holds the sleeve and the nailing strip to the base. Because the outer diameter of the sleeve is less than the diameter of the reduced-diameter lower portion of the bore, upon impact from above, the nailing strip may deflect downwardly unimpeded by the sleeve. The combined vertical dimension of the sleeve and the washer, or flange, is equal to the combined vertical dimension of the pad and the lower portions of the bores. Thus, the sleeve provides a solid line of rigid material between its top end and the base, so that downward driving forces applied via the fastening pin do not precompress the pads.
Preferably, the vertical dimension between the top of the fastening pin and the upper surface of the sleeper is greater than the maximum compression of the pads. This ensures that, upon downward deflection of the nailing strips, the fastening pin will not project above the upper surface of the nailing strip and contact an above-subfloor or floorboard layer.
To produce this sleeper, the nailing strips are cut to a desired length. The bores are then cut vertically through the nailing strips from the upper surface to the lower surface. Thereafter, the compressible pads are secured to the lower surface of the nailing strip. The number of pads and bores will depend upon the lengths of the nailing strips and the desired orientation. With the bores cut and the pads secured, the sleepers are ready for shipping to the job site. Alternately, if desired, these two steps may be performed at the job site.
To install the sleeper, multiple sleepers are laid end to end in spaced, parallel rows. Alternatively, every other sleeper in each row may be offset laterally. The sleeves and washers, or sleeves with flanges, are then placed within the bores. Fastening pins are then driven through the sleeves or through the sleeve and washer and into the base below. When fully extended, the head ends of the fastening pins engage either the top surfaces of the washers or the top surfaces of the flanges, depending upon which embodiment is used. The heads of the fastening pins hold the washer or flanges downwardly against the bottom surfaces of the nailing strips which define the enlarged-diameter upper portions of the base.
Because the sleeve and washer, or the sleeve with the flange, does not compress vertically during installation, the sleeve bears all the vertical force placed upon the nailing strip during installation. As a result, driving of the fasteners into the base does not vertically compress the pads. Moreover, after installation, when the floor system is unloaded, the pads are not held in a compressed state. Accordingly, after installation, the compressible pads retain their full compressive capability, thereby providing optimum resiliency potential throughout the floor system.
The upper flooring layers are then secured to the tops of the nailing strips. According to one preferred construction, a subfloor of panels is secured to the sleepers, and then tongue-and-groove maple floorboards are secured to the panels. Because of the combination of anchored and resilient sleepers, along with a subfloor layer of panels, this particular floor construction provides resiliency with a high degree of uniformity throughout its entire surface area. As indicated previously, recent studies suggest that, in addition to resiliency, uniformity of resiliency also plays a critical role in reducing athletic injury on athletic floor systems and enhancing performance.
Alternatively, the floorboards may be secured directly to the nailing strips. As still another alternative, if desired, the upper flooring layer may comprise one or more wood or non-wooden layers, depending upon the primary commercial use of the floor system.
Because of the relatively few number of parts and simple construction, this inventive sleeper provides conventional stability, resiliency and uniformity in resiliency for a hardwood floor system at a relatively low cost, compared to prior anchored and resilient sleeper-type floor systems.
According to alternative fastening arrangements, the attachment strips may be held with wrapped mesh steel secured to the base, with angled clips or with a transverse band. These embodiments are described in further detail in the detailed description.
These and other features of the invention will be more readily understood in view of the following detailed description and the drawings.